ATL: TROPICAL LOW ex-FRED (ex-07L)

[cycloneye]

WTNT42 KNHC 120233
TCDAT2
TROPICAL STORM FRED DISCUSSION NUMBER 18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072009
1100 PM AST FRI SEP 11 2009

FRED CONTINUES TO PRODUCE DEEP CONVECTION...ALTHOUGH THE COLDEST
CLOUD TOPS ARE NOW DISPLACED MORE THAN A DEGREE NORTH OF THE
LOW-LEVEL CENTER. THIS DISPLACEMENT IS DUE TO ABOUT 20 KNOTS OF
SOUTHERLY SHEAR AS ANALYZED BY THE SHIPS MODEL AND UW-CIMSS. DVORAK
DATA T-NUMBERS AT 0000 UTC WERE 2.5 FROM SAB AND 3.0 FROM TAFB...
AND A QUIKSCAT PASS FROM AROUND 2100 UTC DID NOT SHOW ANY WINDS
HIGHER THAN ABOUT 45 KNOTS. THE INITIAL INTENSITY OF 50 KNOTS IS
BASED ON A BLEND OF THE DATA-T NUMBERS AND ASSUMES THAT RAIN WAS
ATTENUATING THE WIND SIGNAL SOMEWHAT IN THE QUIKSCAT DATA. WITH THE
WIND SHEAR EXPECTED TO CONTINUE...AND FRED MOVING OVER MARGINAL
SSTS AND INTO A MORE STABLE ENVIRONMENT...GRADUAL WEAKENING IS
EXPECTED THROUGH THE PERIOD. THE OFFICIAL FORECAST HAS BEEN
ADJUSTED DOWNWARD FOR THE FIRST 24 HOURS TO ACCOUNT FOR THE INITIAL
INTENSITY...AND IS SIMILAR TO THE PREVIOUS FORECAST AFTER THAT
TIME...IN BEST AGREEMENT WITH THE LGEM MODEL. IT IS POSSIBLE THAT
FRED COULD DISSIPATE BEFORE THE END OF THE 5-DAY PERIOD...AS
INDICATED BY THE SHIPS MODEL.

A 2016 UTC SSMI PASS...A 1941 UTC SSMIS PASS...AND THE QUIKSCAT DATA
ALL SUGGEST THAT THE LOW-LEVEL CENTER OF FRED IS LOCATED FARTHER
SOUTHEAST THAN PREVIOUSLY ESTIMATED. THE INITIAL MOTION ESTIMATE IS
VERY SLOW...060/02. A TURN TOWARD THE NORTH AND THE NORTHWEST WITH
A GRADUAL INCREASE IN FORWARD SPEED IS EXPECTED OVER THE NEXT
COUPLE OF DAYS AS THE DEEP-LAYER TROUGH OVER THE NORTH ATLANTIC
BEGINS TO LIFT OUT. BY 72 HOURS...LOW- TO MID-LEVEL RIDGING WILL
BUILD IN TO THE NORTH OF WHAT IS LEFT OF FRED...AND SHOULD IMPART A
FASTER MOTION TOWARD THE WEST-NORTHWEST THROUGH THE END OF THE
PERIOD. THE TRACK MODEL GUIDANCE IS IN GOOD AGREEMENT ON THIS
SCENARIO...WITH THE EXCEPTION OF THE UKMET...WHICH IS A FAR
SOUTHERN OUTLIER. THE NEW OFFICIAL FORECAST IS ADJUSTED TO THE
RIGHT OF THE PREVIOUS TRACK DUE TO THE MORE EASTWARD INITIAL
POSITION...AND IS NEAR OR JUST TO THE RIGHT OF THE TVCN MODEL
CONSENSUS.

THE INITIAL 34-KT AND 50-KT WIND RADII WERE ADJUSTED BASED ON THE
QUIKSCAT DATA.

FORECAST POSITIONS AND MAX WINDS

INITIAL 12/0300Z 18.0N 33.6W 50 KT
12HR VT 12/1200Z 18.1N 33.5W 40 KT
24HR VT 13/0000Z 18.4N 33.6W 40 KT
36HR VT 13/1200Z 19.2N 34.4W 35 KT
48HR VT 14/0000Z 20.0N 35.9W 30 KT
72HR VT 15/0000Z 22.0N 40.5W 25 KT...REMNANT LOW
96HR VT 16/0000Z 23.5N 46.0W 20 KT...REMNANT LOW
120HR VT 17/0000Z 25.0N 51.5W 20 KT...REMNANT LOW

$$
FORECASTER BRENNAN

[breeze]

000
WTNT32 KNHC 120233
TCPAT2
BULLETIN
TROPICAL STORM FRED ADVISORY NUMBER 18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072009
1100 PM AST FRI SEP 11 2009

...FRED CONTINUES TO WEAKEN...

AT 1100 PM AST...0300 UTC...THE CENTER OF TROPICAL STORM FRED WAS
LOCATED NEAR LATITUDE 18.0 NORTH...LONGITUDE 33.6 WEST OR ABOUT 650
MILES...1045 KM...WEST-NORTHWEST OF THE CAPE VERDE ISLANDS.

FRED IS MOVING VERY SLOWLY TOWARD THE EAST-NORTHEAST NEAR 2 MPH...4
KM/HR. A TURN TOWARD THE NORTH AND THEN THE NORTH-NORTHWEST WITH A
CONTINUED SLOW MOTION IS EXPECTED ON SATURDAY...FOLLOWED BY A TURN
TOWARD THE NORTHWEST WITH AN INCREASE IN FORWARD SPEED ON SUNDAY.

MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 60 MPH...95 KM/HR
...WITH HIGHER GUSTS. ADDITIONAL WEAKENING IS EXPECTED IN THE
NEXT 48 HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 105 MILES...165 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 998 MB...29.47 INCHES.

...SUMMARY OF 1100 PM AST INFORMATION...
LOCATION...18.0N 33.6W
MAXIMUM SUSTAINED WINDS...60 MPH
PRESENT MOVEMENT...EAST-NORTHEAST OR 60 DEGREES AT 2 MPH
MINIMUM CENTRAL PRESSURE...998 MB

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 AM AST.

$$
FORECASTER BRENNAN

[Derek Ortt]

GFS now abandons SF scenario

[ozonepete]

Heh Heh. Fred had a few more tricks up his sleeve. It's starting to look like Fred is pulling away to the northeast. Look at these latest CIMSS steering winds charts for systems rated from 970-999mb. The NHC estimates Fred at 998mb but I think it's a little stronger. Anyway, the steering winds for a storm of Fred's intensity actually lean to the NORTHEAST, and if you've been watching the satellite loops, it's certainly starting to look like a still decently strong TS Fred is accelerating to the northeast. So much for the models! Another (expected) bust for strength, but also for track this time.

[HURAKAN]

Not much here

[gatorcane]

Hi Ozonepete things have changed in 6 hours since you have posted. It is drifting SSE it looks like and will eventually track WNW with a bend West as most of the models show. It won't be shooting of the the Northeast.

Bravo to the models, not sure how they will be wrong here. If anything maybe it will track more left.

[gatorcane]

GFS now abandons SF scenario

YEs it does, at least in the past two runs of the 18Z and 00Z.

But the 06Z shows is more left again but with a sharp turn to the right. I noticed the ECMWF has shifted way left but still not as left as the GFS.



Nice ridging for a change through 5 days and maybe beyond

[gatorcane]

[perk]

Gator it looks like that high we've been talking about is finally materializing.

[perk]

Hi Ozonepete things have changed in 6 hours since you have posted. It is drifting SSE it looks like and will eventually track WNW with a bend West as most of the models show. It won't be shooting of the the Northeast.

Bravo to the models, not sure how they will be wrong here. If anything maybe it will track more left.

Gator you're right, Fred will definately not be moving NE. Latest visible shows it currently stationary.

[gatorcane]

Perk could be...the 06Z HWRF and GFDL show Fred or its remnants bending back due west around 25N or even WSW in the extended range.

That is because they are lifting out a large Upper-level low and associated trough swinging through the Canadian Maritimes and replacing it with a large-scale H5 ridge across Eastern North America....by day 5.

GFDL 06Z:
http://moe.met.fsu.edu/cgi-bin/gfdltc2. ... =Animation

HWRF 06Z:
http://moe.met.fsu.edu/cgi-bin/hwrftc2. ... =Animation

[cycloneye]

000
WTNT42 KNHC 121433
TCDAT2
TROPICAL STORM FRED DISCUSSION NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072009
1100 AM AST SAT SEP 12 2009

SATELLITE IMAGERY INDICATES THAT FRED IS NOW A TIGHT SWIRL OF
LOW-LEVEL CLOUDS...DEVOID OF DEEP CONVECTION. AN EARLIER QUIKSCAT
PASS DID SHOW SEVERAL REALISTIC 35-40 KT WINDS...MOSTLY IN THE
NORTHERN SEMICIRCLE. DVORAK T-NUMBERS HAVE DROPPED TO 1.5 AND 2.0
FROM SAB AND TAFB...RESPECTIVELY. ASSUMING THAT THERE HAS BEEN SOME
ADDITIONAL WEAKENING...THE INITIAL INTENSITY IS LOWERED TO 35 KT.
FURTHER WEAKENING IS FORECAST...AS FRED IS EXPECTED TO ENCOUNTER A
RATHER HOSTILE ENVIRONMENT OF SOUTH-SOUTHWESTERLY SHEAR...MARGINAL
WATER TEMPERATURES...AND DRY MID-LEVEL AIR. IN ALL LIKELIHOOD...
FRED WILL BECOME A REMNANT LOW LATER TODAY OR TONIGHT. GLOBAL
MODELS CONTINUE TO INDICATE SOME CHANCE...ALBEIT REMOTE...OF
REGENERATION TOWARD THE END OF THE FORECAST PERIOD. HOWEVER...THEIR
REPRESENTATION OF FRED SEEMS TOO STRONG GIVEN ITS CURRENT
APPEARANCE...AND ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BECOME
EVEN MORE ADVERSE THAN THEY ARE NOW OVER THE NEXT DAY OR TWO. THE
OFFICIAL FORECAST ASSUMES THAT THE REMNANT CIRCULATION OF FRED WILL
DISSIPATE IN A FEW DAYS.

FRED HAS BEEN MOVING LITTLE DURING THE PAST FEW HOURS. HOWEVER...
RECENT SATELLITE FIXES DO YIELD AN INITIAL MOTION OF 180/03. SINCE
FRED HAS NOW BECOME A SHALLOW SYSTEM...THE EXPECTATION IS THAT IT
WILL MOVE VERY LITTLE DURING THE NEXT 12-24 HOURS WITHIN A RATHER
WEAK LOW-LEVEL FLOW. THEREAFTER...THE REMNANTS OF FRED SHOULD TURN
TOWARD THE NORTHWEST OR EVEN WEST-NORTHWEST...SOUTH OF A BUILDING
LOW-LEVEL RIDGE...WITH SOME INCREASE IN FORWARD SPEED. THE OFFICIAL
FORECAST IS SIMILAR TO THE PREVIOUS PACKAGE BUT SLIGHTLY SLOWER IN
THE SHORT-TERM.

FORECAST POSITIONS AND MAX WINDS

INITIAL 12/1500Z 17.5N 33.7W 35 KT
12HR VT 13/0000Z 17.7N 33.7W 25 KT
24HR VT 13/1200Z 18.4N 34.4W 20 KT...REMNANT LOW
36HR VT 14/0000Z 19.3N 36.4W 20 KT...REMNANT LOW
48HR VT 14/1200Z 20.5N 38.6W 20 KT...REMNANT LOW
72HR VT 15/1200Z 22.5N 44.0W 20 KT...REMNANT LOW
96HR VT 16/1200Z...DISSIPATED

$$
FORECASTER KIMBERLAIN

[Sanibel]

Another naked swirl bee-lining towards Florida:

[gatorcane]

It will be interesting to see if Fred regenerates next week sometime when it is further west.
Several models do regenerate Fred, but as the NHC has mentioned, those models are likely overdoing Fred's current strength.

At any rate, should it regenerate the steering across the Atlantic looks to be west for the next week at least.

[Sanibel]

Remember GFDL had a category 3 headed into recurve along the east coast with Erika.

[perk]

:uarrow: Remember GFDL had a category 3 headed into recurve along the east coast with Erika.

Sanibel i think the point Gator is trying to establish is that the ridge is building back, and he's a bit concerned about what some of the more reliable models are showing with this westward movement, and so am i.

[gatorcane]

NWS Miami indicates the strong ridging that will build in next week across Eastern North America --- but hopefully Fred won't even exist by then anyway:

A DRIER AIRMASS STILL APPEARS AS IF IT WILL SPREAD SOUTHWARD FROM
MONDAY NIGHT INTO TUESDAY...LEADING TO A TEMPORARY LULL IN THE
VERY HIGH RAIN CHANCES FROM PREVIOUS DAYS. HOWEVER...GUIDANCE FROM
THE ECMWF/GFS IS IN GOOD AGREEMENT ON MOISTURE RETURNING TO THE
AREA BEGINNING ON WEDNESDAY...AS STRONG RIDGING OFF THE COAST OF
THE NORTHEASTERN STATES RESULTS IN INCREASING EASTERLY FLOW OVER
SOUTH FLORIDA. WILL ADVERTISE LOW CHANCES OF SHOWERS/STORMS AT
NIGHT ALONG THE EAST COAST...AND HIGHEST AFTERNOON STORM CHANCES
ALONG THE GULF COAST WITH THIS PATTERN.

http://forecast.weather.gov/product.php ... glossary=1

[Lifesgud2]

Guys,

Enough on Fred. Its done. Season is just about over Gator..Come on now!!!

[HURAKAN]

Latest

[AdamFirst]

Quite the naked swirl